This invention relates to a process for producing a bran cereal, an apparatus for producing a bran cereal, and a bran cereal product formed thereby.
It is well known to use an extrusion apparatus for extruding doughs. Several types of extruders are commercially available for use, including single screw extruders and twin screw extruders. Products so extruded are usually of the "expanded" variety although other product types are known as well. Several patents relating to use of bran for food products, and to use of extruders for producing food products, are discussed hereunder. Bran cereal nuggets, referred to hereunder, are commercially available as small bran pieces having a surface which is roughened.
The patent to Fulger et al, U.S. Pat. No. 4,500,558, dated Feb. 19, 1985, relates to modification of bran by extrusion. In this patent, hereinafter referred to as the '558 patent, a bran and water feed having a bran to water ratio of from 5.5:1 to 10:1 is extruded in a counter-rotating twin-screw extruder under high temperature and high shear conditions. The modified bran according to this process is made more readily millable and, when milled, possesses a "mouthfeel" with an absence of grittiness and a greater "functionality" in a food product.
As can be seen from the '558 patent, the combining of the feeds requires combining bran with water to form a feed having a bran to water ratio of from 5.5:1 to 10:1. This is a significant departure from the present invention, which does not include the combining of water to form a feed in this ratio. After the feed is combined, the next step of the patent requires introducing the feed into a counter-rotating twin screw extruder.
The next step disclosed is the extruding of the feed at a temperature of from 150.degree. C. to 180.degree. C. These temperatures are converted to degrees Fahrenheit for comparison to the present invention. In degrees Fahrenheit, the extruding step is conducted in a temperature range according to claim 1 of from 300.degree. F.-356.degree. F. This is in excess of the extruding point temperature range used in the present invention, and gives a different result as seen hereunder.
There is also recited in the '558 patent, a step of developing at the die a shear rate of from 500 to 2000 seconds.sup.-1 in the extruder through which the feed is extruded.
In the specification of the '558 patent, at column 1 lines 33-37, it is stated that the invention relates to a "process for subjecting bran to a high temperature, high shear extrusion in a counter-rotating twin screw extruder which will modify the structure of the bran such that it becomes more readily millable."
Corn bran is mentioned in the '558 patent at column 3 at lines 6-11. Here, the corn bran is referred to as "wet milled corn bran". This further reinforces the teaching that the feed material must be wet upon entering, as claimed in this patent. Furthermore, with wet milled corn bran, the patent teaches in column 3 at lines 22-27 that wet milled corn bran is to be preblended with corn starch, which is necessary to produce a modified product, since attempts to produce a modified product without the starch failed. The attempts to modify the wet milled corn bran are mentioned in column 3 at lines 18-22.
The '558 patent also refers to milling steps which take place after the material exits the extruder. This is seen in column 3 at lines 28-45.
The brans which are taught as being usable in the '558 patent are listed in column 3 at line 49. These include corn, wheat, barley, rye, and combinations of all of these brans. Also, in column 3 of the patent, at lines 50-52, it is taught that these modified bran products can be used in various food products at a level of from 1% to 100% by weight.
In column 3 at lines 52-57 are enumerated such food products including breakfast cereals, expanded cereal products and cereal flakes, but not listing bran cereal "nuggets" products as producible thereby.
The '558 patent also refers to the extrudate as consisting of 70 pounds of small "puffed" material and 40 pounds of hard strips. At lines 51-53 it is taught that the "puffed" material is more desirable and was separated by a sieve. Both materials are then ground in a mill.
U.S. Pat. No. 4,438,146, to Colby et al, relates to a method for preparing cooked wheat products. Here, an apparatus and method for cooking wheat products is shown wherein the products are cooked by extrusion through an extrusion die. The extruder is similar to a conventional twin screw extruding device, and the die plates, shown in FIGS. 2, 3, and 5, cause extrusion of the wheat product into strands. Ground whole wheat is used and mixed with any desired dry ingredients. The cooked edible product is in expanded form. At column 3, at lines 1-3 it is taught that an extrusion aid or lubricant may be added to the dough to modify the extrusion pressures. The preferred extrusion lubricant is an edible oil or fat, the extrusion itself providing the heat necessary for the expansion. As seen in column 3 at lines 11-16, no external heat source is necessary, and because of steam vaporization upon extrusion, the die face itself is cooled so that the outer face of the die has a temperature at the range of 150.degree. F. to 180.degree. F. Water and/or moisture containing product is added to the other ingredients in the cooker, the water being present in a range of 14% to 18% by weight. It is taught in the '146 patent that the level of moisture is important in relation to the development of heat in the die and to the achievment of desired expansions. As taught in column 5 at lines 39-43, the heating and cooking of the dough is primarily done in the die itself. This is also taught in column 5 at lines 33-38, wherein it is stated that the heat generated during cooking in the die can require the temperature to be controlled such as with a water cooling jacket or the like around the body or barrel. Such cooling is to control the temperature range of dough entering the die to between ambient temperature (usually about 68.degree. F.-84.degree. F.) and about 180.degree. F. It is also stated in column 5 at lines 27-29 that "cooking of the dough in the body or the barrel is not necessary and is to be minimized."
The dough, as taught in the '146 patent, in passing through the die generates heat sufficient to form steam and cook the dough enough to condition the gluten so that upon extrusion the dough expands in a desired form as determined by the die configuration. It is also taught that in the die itself the steam is superheated and reaches a temperature of about 250.degree. F. The fluid friction generates the heat.
The die used in the '146 patent has three consecutive disc-shaped plates, each being drilled and tapped for mounting with one another upon the extruder. Another preferred die has only two disc-shaped plates.
The patent to Fulger et al, U.S. Pat. No. 4,431,674, relates to an all natural, ready-to-eat cereal derived from whole cereal grain. The process involves milling and separating the whole grain to produce several fractions, including a bran fraction, an endosperm fraction, and a germ fraction. The bran fraction and any bran material separated out from the ground germ is modified by high temperature, high pressure extrusion in a counter-rotating twin screw extruder.
In U.S. Pat. No. 3,682,652 to Corbin et al, a process for preparing a low calorie snack is taught. Here, corn or rice is mixed with water and then extruded under high pressure from the cooking section 13 to atmospheric pressure. Pressurized steam flashes off and inflates the starch mass to a matrix of tenderized dough which becomes firm with drying. Individual pieces are formed with a cut-off knife. The speed of the knives control the length of the pieces. A toaster-dryer is shown, as well as a cooling unit.
In U.S. Pat. No. 2,120,138 to Mathews et al, a method for producing extruded food products is taught. This patent teaches that heat can be supplied in an extruder through the frictional resistance afforded during the grinding and extruding operations, and that in some instances this heat is sufficient for cooking. This patent also relates to an expanded edible product.
In U.S. Pat. No. 3,703,379, issued to Cummisford et al, double expanded food products and a method for preparing same is taught. The food piece has large voids therein surrounded by thick walls. A secondary expansion such as by deep fat frying or the like causes additional puffing or expanding of the walls. Here, wheat flour and a lipid material is used for the dough.
In U.S. Pat. No. 3,458,321, to Reinhart et al, a method for extrusion cooking of food products is taught. Here, a twin screw extruder is used. The extruder has a feed section, a cooking section, a devolatilizing section, a metering section, and a die. At the devolatilizing section, water and heat are removed from the cooked material, the compressive force release causing moisture to flash from the cooked material and thereby cool and partially dry the cooked material, which is then extruded. A cereal grain such as corn flour or the like is used, in combination with sugar and other ingredients. The dry ingredients are mixed together with a liquid which includes a substantial portion of water. The mixing takes place within the twin screw cooking apparatus. Here, the mechanical forces of the twin screw extruder produce heat due to friction. The pressure applied to the food is taught as being over 1000 psi, and frequently several thousand psi. The food ingredient is gelatinized in the cooking section. Heat jackets are used around the casing 18. Cooling jackets can be used as well. The temperature range in the devolatization zone is approximately 200.degree. F. to about 325.degree. F. At the lower temperature, products are produced which are not puffed, while in the higher temperature range products are produced wherein some puffing has occurred. The temperature range in the metering zone F is between 105.degree. F. and 240.degree. F. The examples teach use of corn together with other ingredients including water. For example in example I of the '321 patent the water content raises the moisture to about 27% moisture by weight.
In U.S. Pat. No. 3,753,729, to Harms et al, a method for preparing food snack compositions is taught. In the patent, a process is taught using a particulate starch material having a specified abrasion rating in combination with a small proportion of an oleaginous material and water. This material is mixed and extruded under pressure at elevated temperature to form a puffed, ready-to-eat product.
In U.S. Pat. No. 897,854, issued to Schluter, Jr., a process for the production of digestible flour from bran is taught. Here, the bran is mixed with boiling water to form a thin pulp, the pulp being heated quickly to about 100.degree. C., and then is dried at a low temperature at about 70.degree. C. until solid. This solid is then ground into a flour.
Bran cereal nuggets are known, and are sold. Here, small nuggets or "buds" are formed which are composed of bran material. The bran material typically includes 100% wheat bran, although other bran materials can be used. However, in the prior art process, corn bran cannot be used to form the bran cereal nuggets. Each bud has a "fibrous" appearance, which provides a pleasant "mouthfeel". These bran cereal nuggets are also crispy and are chewable.
In the prior art process, a batch of ingredients including bran, flour, water, and other ingredients are mixed together with the flavor syrup, dumped onto a conveyor, processed by a grinder into strands, and then dried and toasted. The first step of this conventional process is the pressure cooking for one half hour of, for example, a 100 pound batch of wheat bran, 5% wheat flour, 7.5 pounds of an alternate flour and a flavoring material.
U.S. Pat. No. 1,173,932 (Cockrell) discloses a cereal breakfast food consisting of about 60 percent of wheat bran and the remainder corn meal and oats flour, the latter two items being added to make the bran more palatable. The bran is used for its laxative properties.
U.S. Pat. No. 1,210,589 (Black) discloses a bran biscuit or cake which contains shredded cereal and syrup for nutrition and to make the bran palatable. The shredded cereal can be corn, wheat or rice. About 371/2 percent of bran is used in the formula. Black mentions that bran has laxative properties.
U.S. Pat. No. 1,244,586 (Cockrell) discloses a cereal breakfast food consisting of about 60 percent of wheat bran and the remainder corn meal, wheat and oats. The bran is used for its laxative properties.
U.S. Pat. No. 1,263,609 (Schuyler) discloses a self-rising pancake flour which contains ground rice bran, baking powder, wheat flour, soy flour, rice polish and salt. The mixture can include rice flour. The given example uses 22.5 percent of ground rice bran. The bran is used as a flavorant.
U.S. Pat. No. 1,271,139 (Dickerson) discloses a composition which includes bran (e.g., 15 percent), whole wheat flour, wheat flour, rye flour, etc. The composition is used to make biscuits.
U.S. Pat. No. 3,062,657 (Vollink) discloses an extrusion-cooked, ready-to-eat breakfast cereal flakes which can contain rice flour or bran. A moist comminuted starch-containing cereal mixture is passed through a cooker extruder, the expanded extrudate is tempered and then the cereal material is flaked and toasted. Example 2 uses a starting formula that includes 60 percent of ground whole wheat and 24 percent of bran.
U.S. Pat. No. 4,327,116 (Weith) discloses a bran bakery product from dough composed of 100 parts by weight of bran, 200 to 300 parts by weight of water and 2.5 to 15 parts by weight of carob bean flour (or other vegetable thickening agent). Other conventional dough ingredients such as flavoring agents can be used. Weith specifically mentions wheat bran and rye bran. The prior art section of Weith states that cereal fibers are used as casual therapy of obstipation and intestinal diseases.
U.S. Pat. No. 4,350,714 (Duvall) teaches a corn bran, extrusion-cooked, expanded cereal which further contains corn flour, oat flour, ground limestone, [i.e., CaCO.sub.3 ], sugar, salt, soda, vitamin prefix and colorant. Duvall states that wheat flour and rice flour can be present. Example 1 shows the use of 25 percent of corn bran flour, and the claims recite that sufficient ground corn bran is used to provide 3.5 to 10 weight percent of fiber. The extruded pieces are enrobed in a syrup which includes sugar, coconut oil and water.
British Patent No. 1,561,190 (Weetabix) discloses a food mixture containing bran and a binding agent (starchy material or gum) mixed with water. The mixture is extrusion cooked. The mixture (on a dry basis) contains 10 to 95 percent of bran. The mixture can also contain wheat and rice flours.
German O.S. No. 2,837,294 (Bories et al.) discloses an extrusion cooked foodstuff composed of bran, 20 to 80 percent gluten, 5 to 20 percent, and the balance flour or starch, with the addition of 5 to 20 percent water after charging the mixture to an extruder.
Known foods containing bran include muffins and cereals, such as, All Bran, 100% Bran, Shreddies, Bran Flakes and Bran Crunchies. Wheat bran is found naturally in whole-wheat breads and cereals, can be bought separately for adding to other foods and is rich in dietary fiber.